The invention concerns an apparatus for transporting substrates in vacuum deposition systems with several stations, comprising substrate holders of an approximately plate-like, flat, parallelpiped configuration. These substrate holders, in a vertical position, can be moved across the stations following a given path. They interact with rails provided underneath the substrates which in turn are fastened to the substrate holders. For this purpose, the foot part of the substrate holder has at least two parallel spaced apart rails.
The substrate holders used here are either plates having recesses formed to match the shape of the substrate or they have a frame with bars to which the substrates are fastened. Generally, one substrate holder can hold a plurality of substrates.
U.S. Pat. No. 4,042,128 discloses a transporting apparatus of the aforesaid kind where the plate-like substrates are guided in both their upper and lower longitudinal edges between rollers which can be rotated around perpendicular axes. The main axis of the substrate holder remains in a vertical position. The lower edges of the substrate holder rest in addition on support rollers with a horizontal rotating axis. The lower guide rollers alone, however, are not able to keep the substrate in an exact vertical position and transport it such that a stable positioning is possible with the exclusive aide of the upper guide rollers.
Also known is a transporting apparatus for vacuum deposition systems (EP 254 145B1, to which U.S. Pat. No. 4,765,273 corresponds) which has several stations and includes a roller system to guide and advance essentially two-dimensional substrate holders across the stations in a perpendicular position along a given path. Pairs of guiding rollers which can be rotated around perpendicular axes are disposed in the area of the lower edge of the substrate holder and hold the latter between their rollers. The substrate holders are guided by these roller systems exclusively in the area of their lower edge. The guide rollers have bearing surfaces which are disposed at the lower and upper ends, respectively, of at least one guide roller of each pair of rollers. The respective other guide roller of the same pair has at least one bearing surface and the at least three bearing surfaces of each pair of rollers act as a tilt-safe bracing with respect to the substrate holder.
This known transporting apparatus was based on the task of preventing to a largest possible extent coating material which trickles down from interfering with the coating process.
Further, it also been proposed to provide the substrate holder of a transporting apparatus of a vacuum deposition system with a foot part moving in stationary rails (EP 0 346 815).
Finally, a DE-A 40 29 905.8, to which U.S. application Ser. No. 616,342 corresponds, describes a system for transporting substrates in vacuum deposition systems with several stations by providing rails that are disposed in the area of the foot part of a substrate holder.
For this purpose, each foot part is provided with a pair of vertically disposed, parallel spaced apart rails where the opposing narrow sides have longitudinal grooves that communicate with rollers or slide rails. The latter are disposed on the bottom of the device in a stationary manner and run in rows corresponding to the course of the grooves and are spaced apart in vertical planes on top of one another. The substrate holder has shaft-like recess extending from the top into the area of the foot part and running parallel to the rails. When passing through the stations, a flat, vertically extending heater, which is disposed above the substrate holder at the upper part of the wall, extends into this recess.